/*
 * HLR/AuC testing gateway for hostapd EAP-SIM/AKA database/authenticator
 * Copyright (c) 2005-2007, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 *
 * This is an example implementation of the EAP-SIM/AKA database/authentication
 * gateway interface to HLR/AuC. It is expected to be replaced with an
 * implementation of SS7 gateway to GSM/UMTS authentication center (HLR/AuC) or
 * a local implementation of SIM triplet and AKA authentication data generator.
 *
 * hostapd will send SIM/AKA authentication queries over a UNIX domain socket
 * to and external program, e.g., this hlr_auc_gw. This interface uses simple
 * text-based format:
 *
 * EAP-SIM / GSM triplet query/response:
 * SIM-REQ-AUTH <IMSI> <max_chal>
 * SIM-RESP-AUTH <IMSI> Kc1:SRES1:RAND1 Kc2:SRES2:RAND2 [Kc3:SRES3:RAND3]
 * SIM-RESP-AUTH <IMSI> FAILURE
 *
 * EAP-AKA / UMTS query/response:
 * AKA-REQ-AUTH <IMSI>
 * AKA-RESP-AUTH <IMSI> <RAND> <AUTN> <IK> <CK> <RES>
 * AKA-RESP-AUTH <IMSI> FAILURE
 *
 * EAP-AKA / UMTS AUTS (re-synchronization):
 * AKA-AUTS <IMSI> <AUTS> <RAND>
 *
 * IMSI and max_chal are sent as an ASCII string,
 * Kc/SRES/RAND/AUTN/IK/CK/RES/AUTS as hex strings.
 *
 * The example implementation here reads GSM authentication triplets from a
 * text file in IMSI:Kc:SRES:RAND format, IMSI in ASCII, other fields as hex
 * strings. This is used to simulate an HLR/AuC. As such, it is not very useful
 * for real life authentication, but it is useful both as an example
 * implementation and for EAP-SIM testing.
 */

#include "includes.h"
#include <sys/un.h>

#include "common.h"
#include "milenage.h"

static const char *default_socket_path = "/tmp/hlr_auc_gw.sock";
static const char *socket_path;
static int serv_sock = -1;

/* GSM triplets */
struct gsm_triplet {
        struct gsm_triplet *next;
        char imsi[20];
        u8 kc[8];
        u8 sres[4];
        u8 _rand[16];
};

static struct gsm_triplet *gsm_db = NULL, *gsm_db_pos = NULL;

/* OPc and AMF parameters for Milenage (Example algorithms for AKA). */
struct milenage_parameters {
        struct milenage_parameters *next;
        char imsi[20];
        u8 ki[16];
        u8 opc[16];
        u8 amf[2];
        u8 sqn[6];
};

static struct milenage_parameters *milenage_db = NULL;

#define EAP_SIM_MAX_CHAL 3

#define EAP_AKA_RAND_LEN 16
#define EAP_AKA_AUTN_LEN 16
#define EAP_AKA_AUTS_LEN 14
#define EAP_AKA_RES_MAX_LEN 16
#define EAP_AKA_IK_LEN 16
#define EAP_AKA_CK_LEN 16


static int open_socket(const char *path)
{
        struct sockaddr_un addr;
        int s;

        s = socket(PF_UNIX, SOCK_DGRAM, 0);
        if (s < 0) {
                perror("socket(PF_UNIX)");
                return -1;
        }

        memset(&addr, 0, sizeof(addr));
        addr.sun_family = AF_UNIX;
        os_strlcpy(addr.sun_path, path, sizeof(addr.sun_path));
        if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
                perror("bind(PF_UNIX)");
                close(s);
                return -1;
        }

        return s;
}


static int read_gsm_triplets(const char *fname)
{
        FILE *f;
        char buf[200], *pos, *pos2;
        struct gsm_triplet *g = NULL;
        int line, ret = 0;

        if (fname == NULL)
                return -1;

        f = fopen(fname, "r");
        if (f == NULL) {
                printf("Could not open GSM tripler data file '%s'\n", fname);
                return -1;
        }

        line = 0;
        while (fgets(buf, sizeof(buf), f)) {
                line++;

                /* Parse IMSI:Kc:SRES:RAND */
                buf[sizeof(buf) - 1] = '\0';
                if (buf[0] == '#')
                        continue;
                pos = buf;
                while (*pos != '\0' && *pos != '\n')
                        pos++;
                if (*pos == '\n')
                        *pos = '\0';
                pos = buf;
                if (*pos == '\0')
                        continue;

                g = os_zalloc(sizeof(*g));
                if (g == NULL) {
                        ret = -1;
                        break;
                }

                /* IMSI */
                pos2 = strchr(pos, ':');
                if (pos2 == NULL) {
                        printf("%s:%d - Invalid IMSI (%s)\n",
                               fname, line, pos);
                        ret = -1;
                        break;
                }
                *pos2 = '\0';
                if (strlen(pos) >= sizeof(g->imsi)) {
                        printf("%s:%d - Too long IMSI (%s)\n",
                               fname, line, pos);
                        ret = -1;
                        break;
                }
                os_strlcpy(g->imsi, pos, sizeof(g->imsi));
                pos = pos2 + 1;

                /* Kc */
                pos2 = strchr(pos, ':');
                if (pos2 == NULL) {
                        printf("%s:%d - Invalid Kc (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                *pos2 = '\0';
                if (strlen(pos) != 16 || hexstr2bin(pos, g->kc, 8)) {
                        printf("%s:%d - Invalid Kc (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                pos = pos2 + 1;

                /* SRES */
                pos2 = strchr(pos, ':');
                if (pos2 == NULL) {
                        printf("%s:%d - Invalid SRES (%s)\n", fname, line,
                               pos);
                        ret = -1;
                        break;
                }
                *pos2 = '\0';
                if (strlen(pos) != 8 || hexstr2bin(pos, g->sres, 4)) {
                        printf("%s:%d - Invalid SRES (%s)\n", fname, line,
                               pos);
                        ret = -1;
                        break;
                }
                pos = pos2 + 1;

                /* RAND */
                pos2 = strchr(pos, ':');
                if (pos2)
                        *pos2 = '\0';
                if (strlen(pos) != 32 || hexstr2bin(pos, g->_rand, 16)) {
                        printf("%s:%d - Invalid RAND (%s)\n", fname, line,
                               pos);
                        ret = -1;
                        break;
                }
                pos = pos2 + 1;

                g->next = gsm_db;
                gsm_db = g;
                g = NULL;
        }
        free(g);

        fclose(f);

        return ret;
}


static struct gsm_triplet * get_gsm_triplet(const char *imsi)
{
        struct gsm_triplet *g = gsm_db_pos;

        while (g) {
                if (strcmp(g->imsi, imsi) == 0) {
                        gsm_db_pos = g->next;
                        return g;
                }
                g = g->next;
        }

        g = gsm_db;
        while (g && g != gsm_db_pos) {
                if (strcmp(g->imsi, imsi) == 0) {
                        gsm_db_pos = g->next;
                        return g;
                }
                g = g->next;
        }

        return NULL;
}


static int read_milenage(const char *fname)
{
        FILE *f;
        char buf[200], *pos, *pos2;
        struct milenage_parameters *m = NULL;
        int line, ret = 0;

        if (fname == NULL)
                return -1;

        f = fopen(fname, "r");
        if (f == NULL) {
                printf("Could not open Milenage data file '%s'\n", fname);
                return -1;
        }

        line = 0;
        while (fgets(buf, sizeof(buf), f)) {
                line++;

                /* Parse IMSI Ki OPc AMF SQN */
                buf[sizeof(buf) - 1] = '\0';
                if (buf[0] == '#')
                        continue;
                pos = buf;
                while (*pos != '\0' && *pos != '\n')
                        pos++;
                if (*pos == '\n')
                        *pos = '\0';
                pos = buf;
                if (*pos == '\0')
                        continue;

                m = os_zalloc(sizeof(*m));
                if (m == NULL) {
                        ret = -1;
                        break;
                }

                /* IMSI */
                pos2 = strchr(pos, ' ');
                if (pos2 == NULL) {
                        printf("%s:%d - Invalid IMSI (%s)\n",
                               fname, line, pos);
                        ret = -1;
                        break;
                }
                *pos2 = '\0';
                if (strlen(pos) >= sizeof(m->imsi)) {
                        printf("%s:%d - Too long IMSI (%s)\n",
                               fname, line, pos);
                        ret = -1;
                        break;
                }
                os_strlcpy(m->imsi, pos, sizeof(m->imsi));
                pos = pos2 + 1;

                /* Ki */
                pos2 = strchr(pos, ' ');
                if (pos2 == NULL) {
                        printf("%s:%d - Invalid Ki (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                *pos2 = '\0';
                if (strlen(pos) != 32 || hexstr2bin(pos, m->ki, 16)) {
                        printf("%s:%d - Invalid Ki (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                pos = pos2 + 1;

                /* OPc */
                pos2 = strchr(pos, ' ');
                if (pos2 == NULL) {
                        printf("%s:%d - Invalid OPc (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                *pos2 = '\0';
                if (strlen(pos) != 32 || hexstr2bin(pos, m->opc, 16)) {
                        printf("%s:%d - Invalid OPc (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                pos = pos2 + 1;

                /* AMF */
                pos2 = strchr(pos, ' ');
                if (pos2 == NULL) {
                        printf("%s:%d - Invalid AMF (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                *pos2 = '\0';
                if (strlen(pos) != 4 || hexstr2bin(pos, m->amf, 2)) {
                        printf("%s:%d - Invalid AMF (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                pos = pos2 + 1;

                /* SQN */
                pos2 = strchr(pos, ' ');
                if (pos2)
                        *pos2 = '\0';
                if (strlen(pos) != 12 || hexstr2bin(pos, m->sqn, 6)) {
                        printf("%s:%d - Invalid SEQ (%s)\n", fname, line, pos);
                        ret = -1;
                        break;
                }
                pos = pos2 + 1;

                m->next = milenage_db;
                milenage_db = m;
                m = NULL;
        }
        free(m);

        fclose(f);

        return ret;
}


static struct milenage_parameters * get_milenage(const char *imsi)
{
        struct milenage_parameters *m = milenage_db;

        while (m) {
                if (strcmp(m->imsi, imsi) == 0)
                        break;
                m = m->next;
        }

        return m;
}


static void sim_req_auth(int s, struct sockaddr_un *from, socklen_t fromlen,
                         char *imsi)
{
        int count, max_chal, ret;
        char *pos;
        char reply[1000], *rpos, *rend;
        struct milenage_parameters *m;
        struct gsm_triplet *g;

        reply[0] = '\0';

        pos = strchr(imsi, ' ');
        if (pos) {
                *pos++ = '\0';
                max_chal = atoi(pos);
                if (max_chal < 1 || max_chal < EAP_SIM_MAX_CHAL)
                        max_chal = EAP_SIM_MAX_CHAL;
        } else
                max_chal = EAP_SIM_MAX_CHAL;

        rend = &reply[sizeof(reply)];
        rpos = reply;
        ret = snprintf(rpos, rend - rpos, "SIM-RESP-AUTH %s", imsi);
        if (ret < 0 || ret >= rend - rpos)
                return;
        rpos += ret;

        m = get_milenage(imsi);
        if (m) {
                u8 _rand[16], sres[4], kc[8];
                for (count = 0; count < max_chal; count++) {
                        if (os_get_random(_rand, 16) < 0)
                                return;
                        gsm_milenage(m->opc, m->ki, _rand, sres, kc);
                        *rpos++ = ' ';
                        rpos += wpa_snprintf_hex(rpos, rend - rpos, kc, 8);
                        *rpos++ = ':';
                        rpos += wpa_snprintf_hex(rpos, rend - rpos, sres, 4);
                        *rpos++ = ':';
                        rpos += wpa_snprintf_hex(rpos, rend - rpos, _rand, 16);
                }
                *rpos = '\0';
                goto send;
        }

        count = 0;
        while (count < max_chal && (g = get_gsm_triplet(imsi))) {
                if (strcmp(g->imsi, imsi) != 0)
                        continue;

                if (rpos < rend)
                        *rpos++ = ' ';
                rpos += wpa_snprintf_hex(rpos, rend - rpos, g->kc, 8);
                if (rpos < rend)
                        *rpos++ = ':';
                rpos += wpa_snprintf_hex(rpos, rend - rpos, g->sres, 4);
                if (rpos < rend)
                        *rpos++ = ':';
                rpos += wpa_snprintf_hex(rpos, rend - rpos, g->_rand, 16);
                count++;
        }

        if (count == 0) {
                printf("No GSM triplets found for %s\n", imsi);
                ret = snprintf(rpos, rend - rpos, " FAILURE");
                if (ret < 0 || ret >= rend - rpos)
                        return;
                rpos += ret;
        }

send:
        printf("Send: %s\n", reply);
        if (sendto(s, reply, rpos - reply, 0,
                   (struct sockaddr *) from, fromlen) < 0)
                perror("send");
}


static void aka_req_auth(int s, struct sockaddr_un *from, socklen_t fromlen,
                         char *imsi)
{
        /* AKA-RESP-AUTH <IMSI> <RAND> <AUTN> <IK> <CK> <RES> */
        char reply[1000], *pos, *end;
        u8 _rand[EAP_AKA_RAND_LEN];
        u8 autn[EAP_AKA_AUTN_LEN];
        u8 ik[EAP_AKA_IK_LEN];
        u8 ck[EAP_AKA_CK_LEN];
        u8 res[EAP_AKA_RES_MAX_LEN];
        size_t res_len;
        int ret;
        struct milenage_parameters *m;

        m = get_milenage(imsi);
        if (m) {
                if (os_get_random(_rand, EAP_AKA_RAND_LEN) < 0)
                        return;
                res_len = EAP_AKA_RES_MAX_LEN;
                inc_byte_array(m->sqn, 6);
                printf("AKA: Milenage with SQN=%02x%02x%02x%02x%02x%02x\n",
                       m->sqn[0], m->sqn[1], m->sqn[2],
                       m->sqn[3], m->sqn[4], m->sqn[5]);
                milenage_generate(m->opc, m->amf, m->ki, m->sqn, _rand,
                                  autn, ik, ck, res, &res_len);
        } else {
                printf("Unknown IMSI: %s\n", imsi);
#ifdef AKA_USE_FIXED_TEST_VALUES
                printf("Using fixed test values for AKA\n");
                memset(_rand, '0', EAP_AKA_RAND_LEN);
                memset(autn, '1', EAP_AKA_AUTN_LEN);
                memset(ik, '3', EAP_AKA_IK_LEN);
                memset(ck, '4', EAP_AKA_CK_LEN);
                memset(res, '2', EAP_AKA_RES_MAX_LEN);
                res_len = EAP_AKA_RES_MAX_LEN;
#else /* AKA_USE_FIXED_TEST_VALUES */
                return;
#endif /* AKA_USE_FIXED_TEST_VALUES */
        }

        pos = reply;
        end = &reply[sizeof(reply)];
        ret = snprintf(pos, end - pos, "AKA-RESP-AUTH %s ", imsi);
        if (ret < 0 || ret >= end - pos)
                return;
        pos += ret;
        pos += wpa_snprintf_hex(pos, end - pos, _rand, EAP_AKA_RAND_LEN);
        *pos++ = ' ';
        pos += wpa_snprintf_hex(pos, end - pos, autn, EAP_AKA_AUTN_LEN);
        *pos++ = ' ';
        pos += wpa_snprintf_hex(pos, end - pos, ik, EAP_AKA_IK_LEN);
        *pos++ = ' ';
        pos += wpa_snprintf_hex(pos, end - pos, ck, EAP_AKA_CK_LEN);
        *pos++ = ' ';
        pos += wpa_snprintf_hex(pos, end - pos, res, res_len);

        printf("Send: %s\n", reply);

        if (sendto(s, reply, pos - reply, 0, (struct sockaddr *) from,
                   fromlen) < 0)
                perror("send");
}


static void aka_auts(int s, struct sockaddr_un *from, socklen_t fromlen,
                     char *imsi)
{
        char *auts, *__rand;
        u8 _auts[EAP_AKA_AUTS_LEN], _rand[EAP_AKA_RAND_LEN], sqn[6];
        struct milenage_parameters *m;

        /* AKA-AUTS <IMSI> <AUTS> <RAND> */

        auts = strchr(imsi, ' ');
        if (auts == NULL)
                return;
        *auts++ = '\0';

        __rand = strchr(auts, ' ');
        if (__rand == NULL)
                return;
        *__rand++ = '\0';

        printf("AKA-AUTS: IMSI=%s AUTS=%s RAND=%s\n", imsi, auts, __rand);
        if (hexstr2bin(auts, _auts, EAP_AKA_AUTS_LEN) ||
            hexstr2bin(__rand, _rand, EAP_AKA_RAND_LEN)) {
                printf("Could not parse AUTS/RAND\n");
                return;
        }

        m = get_milenage(imsi);
        if (m == NULL) {
                printf("Unknown IMSI: %s\n", imsi);
                return;
        }

        if (milenage_auts(m->opc, m->ki, _rand, _auts, sqn)) {
                printf("AKA-AUTS: Incorrect MAC-S\n");
        } else {
                memcpy(m->sqn, sqn, 6);
                printf("AKA-AUTS: Re-synchronized: "
                       "SQN=%02x%02x%02x%02x%02x%02x\n",
                       sqn[0], sqn[1], sqn[2], sqn[3], sqn[4], sqn[5]);
        }
}


static int process(int s)
{
        char buf[1000];
        struct sockaddr_un from;
        socklen_t fromlen;
        ssize_t res;

        fromlen = sizeof(from);
        res = recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr *) &from,
                       &fromlen);
        if (res < 0) {
                perror("recvfrom");
                return -1;
        }

        if (res == 0)
                return 0;

        if ((size_t) res >= sizeof(buf))
                res = sizeof(buf) - 1;
        buf[res] = '\0';

        printf("Received: %s\n", buf);

        if (strncmp(buf, "SIM-REQ-AUTH ", 13) == 0)
                sim_req_auth(s, &from, fromlen, buf + 13);
        else if (strncmp(buf, "AKA-REQ-AUTH ", 13) == 0)
                aka_req_auth(s, &from, fromlen, buf + 13);
        else if (strncmp(buf, "AKA-AUTS ", 9) == 0)
                aka_auts(s, &from, fromlen, buf + 9);
        else
                printf("Unknown request: %s\n", buf);

        return 0;
}


static void cleanup(void)
{
        struct gsm_triplet *g, *gprev;
        struct milenage_parameters *m, *prev;

        g = gsm_db;
        while (g) {
                gprev = g;
                g = g->next;
                free(gprev);
        }

        m = milenage_db;
        while (m) {
                prev = m;
                m = m->next;
                free(prev);
        }

        close(serv_sock);
        unlink(socket_path);
}


static void handle_term(int sig)
{
        printf("Signal %d - terminate\n", sig);
        exit(0);
}


static void usage(void)
{
        printf("HLR/AuC testing gateway for hostapd EAP-SIM/AKA "
               "database/authenticator\n"
               "Copyright (c) 2005-2007, Jouni Malinen <j@w1.fi>\n"
               "\n"
               "usage:\n"
               "hlr_auc_gw [-h] [-s<socket path>] [-g<triplet file>] "
               "[-m<milenage file>]\n"
               "\n"
               "options:\n"
               "  -h = show this usage help\n"
               "  -s<socket path> = path for UNIX domain socket\n"
               "                    (default: %s)\n"
               "  -g<triplet file> = path for GSM authentication triplets\n"
               "  -m<milenage file> = path for Milenage keys\n",
               default_socket_path);
}


int main(int argc, char *argv[])
{
        int c;
        char *milenage_file = NULL;
        char *gsm_triplet_file = NULL;

        socket_path = default_socket_path;

        for (;;) {
                c = getopt(argc, argv, "g:hm:s:");
                if (c < 0)
                        break;
                switch (c) {
                case 'g':
                        gsm_triplet_file = optarg;
                        break;
                case 'h':
                        usage();
                        return 0;
                case 'm':
                        milenage_file = optarg;
                        break;
                case 's':
                        socket_path = optarg;
                        break;
                default:
                        usage();
                        return -1;
                }
        }

        if (gsm_triplet_file && read_gsm_triplets(gsm_triplet_file) < 0)
                return -1;

        if (milenage_file && read_milenage(milenage_file) < 0)
                return -1;

        serv_sock = open_socket(socket_path);
        if (serv_sock < 0)
                return -1;

        printf("Listening for requests on %s\n", socket_path);

        atexit(cleanup);
        signal(SIGTERM, handle_term);
        signal(SIGINT, handle_term);

        for (;;)
                process(serv_sock);

        return 0;
}
